The present invention relates to a magnetic refrigerator and refrigeration method which utilize the magnetocaloric effect of a magnetic substance. More particularly, it is intended to provide a magnetic refrigerator which can operate at a high efficiency and over a wide range of temperatures without requiring a regenerator.
As described in any of the official gazette of Japanese Patent Application Laid-open No. 21958/1984, the specification of U.S. Pat. No. 4,332,135, the specification of U.S. Pat. No. 4,441,325, etc., a prior-art apparatus has needed a regenerator for periodically absorbing and radiating heat in a case where a magnetic refrigeration cycle is to be realized by the magnetic Stirling cycle or the magnetic Ericsson cycle.
With the prior art, when it is intended to obtain a regenerator having an excellent performance especially in a temperature range of 1.degree. K. to 20.degree. K., there is no suitable material (solid, liquid or gas) of great specific heat. This has led to the disadvantages that the volume of the regenerator becomes very large in the magnetic refrigeration cycle involving the regenerator, that a method of heat exchange becomes very complicated and that the efficiency of the regenerator is very low.
Moreover, with the prior art, in a case where an ideal magnetic refrigeration cycle is not attained due to the thermomagnetic characteristic of a magnetic working substance, the magnetic refrigeration cycle cannot be realized.